1. Field of the Invention
The present invention relates generally to a circuit and method for detecting current, and more particularly, to a current detection circuit and method for detecting a current that is output to a resonator for wireless power transmission in a wireless power transmitter.
2. Description of Related Art
In recent years, wireless (or non-contact) charging technology has been developed and applied to many electronic devices. The wireless charging technology is a charging technology based on wireless power transmission and reception. Wireless charging technology, enables a battery of a device, for example, a cellular phone, to be automatically charged when the user simply places the cellular phone on a charging pad without connecting the cellular phone to a separate charging connector. The wireless charging technology further increases the waterproof performance of electronic products by charging the electronic products wirelessly, and increases the portability of electronic devices since a wired charger is not required.
Charging based on the resonance wireless charging scheme is performed as follows. If a wireless power receiver (e.g., a mobile terminal) requiring to be charged, is positioned on a wireless power transmitter (e.g., a charging pad) transmitting wireless power, the wireless power transmitter wirelessly charges the wireless power receiver. In this wireless charging scheme, it is ideal that the amount of transmission power in the wireless power transmitter is matched with the amount of reception power in the wireless power receiver. However, the amount of reception power may inevitably be less than the amount of transmission power due to various internal and external factors which occur in the power transmission path. During wireless charging, the impedance is changed depending on the environment surrounding the antenna or the resonator, causing a decrease in the efficiency and output power. Therefore, there is a need for improving power transmission efficiency.
Accordingly, if the power, voltage and current delivered to the antenna or the resonator of the wireless receiver, which is an output load, can be accurately measured, the performance of the power transmission efficiency is improved.